Definition of sperm morphological examination: Sperm morphological examination is to understand the proportion of normal sperm to that of variant sperm in the physiological and pathological range, and is an important indicator of male fertility. Structure of sperm morphology: Normal sperm resembles a tadpole and consists of three parts: head, body and tail. The head is slightly flat, ovoid, with a regular outline and a clear acrosome, with the acrosome cap covering more than l/3 of the head surface and a translucent area at the front of the sperm head. The head is 3-5 um long and 2-3 um wide, with an aspect ratio of 1.5-2:1. The aspect ratio is one of the important data to determine whether the sperm morphology is normal. The middle part of the body is elongated, less than 1/3 of the head width, straight and regular in outline, in a straight line with the longitudinal axis of the head, about 5-7um long and lum wide. the tail is elongated, regular in appearance and not curled, generally 50-60um long. the HE stained acrosome is light red, the nucleus is located at the base of the acrosome, purplish red, and the tail is light purplish red. With modified Pap staining, the acrosome is light green, the nucleus is purplish-red and the tail is green. There is a wide variety of abnormal sperm morphology, with more than 70 variants. The actual classification is to divide the sperm into those with normal heads (ovoid heads), indeterminate heads (irregular heads), gradually thinning heads, large heads, small heads and immature heads (underdeveloped ones). There is a lack of uniform classification criteria. The main means of sperm morphology: sperm smear staining is the main means of analyzing sperm morphology. Normal sperm and variant sperm within the physiological and pathological range can only be analyzed by staining. Common methods: The commonly used method is the smear method. When the sperm count is <10×109/L, the semen should be centrifuged at 500rpm/10min and the sediment smear taken. When the sperm count is >10×109/L, l drops of semen should be taken directly for smear and dried naturally in air. There are many methods of staining semen smears, which can be chosen according to clinical or research needs. Commonly used are HE (hematoxylin-eosin) staining method or Rui-Ki staining method, and special identification of morphology can be done by modified Pap staining method. Abnormal sperm in normal semen should be 10-15%, and >20% is abnormal. The morphology of abnormal sperm is often associated with infection, trauma, androgenic changes or chemical and genetic influences. Non-specific infections of the reproductive system can lead to an increased proportion of acromegalic and indeterminate head sperm. Varicocele can cause swelling or defects in the head or body of the sperm due to high temperature in the scrotum and lack of oxygen in the testicular tissue caused by poor venous reflux. Immature sperm and other cytoplasmic droplets of germ cells and sperm cell bodies can appear in semen when taking hormones or certain chemicals.